In Shizuka prefecture, there is a city named Numazu. In 2023, It is the year that was made 100 years ago.
There was village name Numazu before 1923, but in 1923 Numazu merged with Yanagihara village. After that, more village merged to Numazu and there is now Numazu city.
This building was used by the emperor of Japan, aristocracy. It is good for tourism, and it's made o a rare structure. When you go inside you can learn the history of this building.
This building is a minor kofun. Kofun is an old grave that is made for authority. Kofun is made because it won't disdain after death. This kofun is considered older than normal kofun. Because it found some old stuff on Kofun and it became popular Kofun on Numazu.
Reference:沼津御用邸記念公園 (numazu-goyotei.com)
「沼津市」になるまで (city.numazu.shizuoka.jp)
高尾山古墳(たかおさんこふん)(city.numazu.shizuoka.jp)